Piping systems, particularly those carrying crude oil, oil products, and natural gas are subject to chemical corrosion (primarily due to carbon dioxide and hydrogen sulfide) and to corrosion caused by microbial growth in the piping systems, so called MIC (microbiologically influenced corrosion). MIC is caused by both anaerobic and aerobic bacteria and therefore can occur in both aerobic and anaerobic systems and systems which have a mix of conditions. It has been found that MIC also occurs in fire protection sprinkler pipeline systems. The interior environment of FPS (fire protection systems) have similar mixed anaerobic/aerobic conditions as oil transmission pipelines and are equally prone to the growth of microorganisms. In addition, water often stands stagnant for long periods in these FPS, and acts as a breeding ground for the very microorganisms that cause the MIC.
One method of dealing with microorganisms and corrosion of a fire protection piping system has been detailed in U.S. Pat. No. 6,076,536 to Ludwig et. al. Ludwig discloses the introduction of an anti-microbial agent into the water residing in the system after the system has been chemically cleaned in a previous step and passivated in a second step. This multi-step cleaning/passivation procedure requires isolation and opening the system, and the anti-microbial treatment presents the possibility of exposing humans to potentially harmful levels of the anti-microbial agent in the event the system is activated or opened for servicing.
Another method is disclosed in U.S. Pat. No. 5,803,180 to Talley. In this method, the stagnant water is treated to have a high pH, which retards microbial growth. This method also involves multi-step preparation of the pipeline and requires extensive procedures to electrically isolate ferrous members and nonferrous members of the piping system to prevent galvanic corrosion, which would otherwise occur in the presence of the residual basic fluid. This also presents the possibility of exposing humans to the caustic fluid if the system is activated or opened for servicing.
Another method of microorganism control within fire protection systems is detailed in U.S. Pat. No. 6,221,263 to Pope, et. al. This involves a device and method for automatically treating water as it enters a fire protection sprinkler system (FPS) to kill microbes introduced with the water. This device and method, again, introduce an antimicrobial treatment, which, again presents the possibility of exposing humans to potentially harmful levels of the anti-microbial agent in the event the system is activated or opened for servicing.
Another typical prior art method of cleaning pipelines such as those used in oil transmission involve forcing a “pig” through the line to remove sludge clinging to the walls. However, in some sections of pipeline, no facilities for “pigging” the line have been installed or cannot be installed. Other prior art methods involve chemical cleaning of the line, but this requires shutting down a section of line for such treatment.
Still other chemical treatments for both cleaning and corrosion protection have been injected into the fluid transmitted through the pipeline. Such a system is disclosed in U.S. Pat. No. 6,042,632. In such systems, the anticorrosive material is continuously added to the fluid to be transported through the pipeline. The system works well when the fluid is first placed in a storage tank and then put into the pipeline. The anticorrosive material is easily added to the fluid in the storage tank before the fluid is placed in the pipeline. If the fluids are not first placed a storage tank prior to being transported through the pipeline, then expensive high pressure pumping equipment is required to introduce the anticorrosive material into the pipeline while the fluid is transported.
Several classes of chemical agents have been used as anticorrosive agents in pipelines. Some of the chemical agents are known to produce coatings that have antimicrobial properties. An example of an anti-microbial coating is disclosed in U.S. Pat. No. 6,030,632 to Sawan et. al. Anticorrosive agents which have been applied to pipelines have been disclosed in U.S. Pat. No. 6,117,558 to Spellane et. al, U.S. Pat. No. 6,042,750 to Burlew, and U.S. Pat. No. 4,197,091 to Gainer. These patents are directed to the application of coatings or polymeric coatings which contain or are the reaction product of aldehydes, amines, carboxylic acids (both mono and poly functional), pyridines, imidazols, anilines, fatty acids both saturated and unsaturated, diamines, and aliphatic quaternary ammonium salts.
Other methods of treating pipelines have been detailed in U.S. Pat. No. 5,046,289 to Bengel et. al, U.S. Pat. No. 5,735,955 to Monaghan et. al, and U.S. Pat. No. 5,213,120 to Dickson. In the '289 patent, a mechanical head which ablates the surface of the pipe is passed down through the pipe. This is impractical for long lengths of pipe such as an oil transmission line, and costly for a closed system such as a fire protection system. Both the '120 and '955 patents utilize a dispersion head passed down the pipeline, which generates foam containing the substance used to treat the pipeline. Contact of the foam with the interior surface of the pipeline disperses the treatment agent on the interior of the pipeline surface.
While the use of a mechanical head to disperse foam within a pipeline has the same shortcomings as the use of a mechanical cleaning head, the use of foam to carry the treating agent down of a pipeline and bringing the treating agent against all the interior surfaces is something that can be practiced with minimal support equipment and no particular line fittings. The present invention makes use of this principle to disperse agents to clean and treat the interior of a pipeline or fire protection system.
The present invention discloses foamed compositions which when applied to the inside surface of a pipe helps reduce or prevent chemical corrosion or microbiologically influenced corrosion of the pipe surface. The present invention also discloses methods and apparatus for cleaning and applying this composition to the interior surface of existing fire protection systems and pipelines. The composition can also be applied to the raw pipe stock used to construct fire protection systems and pipeline.